ORA-12557 TNS:protocol adapter not loadable

The ORA-12577 error is related to Windows Environment or Oracle Home PATH because sqlplus command works smoothly when I execute it inside ORACLE_HOME\bin . Its because of two or more oracle installs (say database and companion) in separate ORACLE_HOMEs on that machine unset the ORACLE_HOME value in your window For Details please follow the following steps and hope so you will get the solution. http://www.dba-oracle.com/t_ora_12577.htm

The base problem is that there are DLLs missing in the Oracle instant client installation that exist in the RDBMS server installation that the application requires. This is why switching Oracle homes from client_1 to db_1 works, rather than it being a purely a PATH problem.

sqlplus works in either situation because it uses the minimal set of DLLs which exist in both Oracle installations.